Muslim pilgrims perform the evening prayer near the Grand Mosque in the holy city of Mecca, Saudi Arabia on Nov. 12. The annual pilgrimage, or hajj, must be performed at least once in their life of all believers who have the health and the means to make the journey.

Muslim pilgrims walk through the streets of Mecca after the close of evening prayers on Nov. 12.

Pilgrims sit on top of a bus heading to the Grand Mosque in Mecca late on Nov. 13. Around 2.5 million pilgrims are expected to make the journey this year.

Pilgrims rest along a road leading into Mina, three miles east of Mecca, on Nov. 14.

Pilgrims walk through a tunnel following evening prayers in Mecca on Nov. 12.

Saudi boys sort through water containers used for the Zamzam well in Mecca on Nov. 7. According to Islamic belief, Zamzam is a miraculously-generated well from God. Millions of pilgrims visit and drink from the water source each year while performing the Hajj.

Saudi special forces take part in a military parade in Mecca on Nov. 10.

A man stands watching the newly-opened Holy Sites metro light rail in Mecca on Nov. 2. The Chinese-built monorail project will link Mecca with the holy sites of Mina, Arafat, and Muzdalifah.

Pilgrims perform the Friday prayer under the shadow of minarets on Nov. 12.

A pilgrim looks at Mecca from the top of Noor mountain where the Hiraa cave is located late on Nov. 13. According to Muslim believers, the Prophet Mohammed received his first message to preach Islam while praying in the cave.